/Engine/Source/Runtime/Engine/Public/Slate/SGameLayerManager.h
virtual void SetWindowTitleBarState ( const [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > & TitleBarContent, EWindowTitleBarMode Mode, bool bTitleBarDragEnabled, bool bWindowButtonsVisible, bool bTitleBarVisible )